Ventilated foot orthotic

ABSTRACT

A thin, lightweight, ventilated foot orthotic is formed of a strong, resilient thermoplastic material with a contoured shape providing arch support partially spaced above the insole of the foot wear in which the foot orthotic is used.

RELATED APPLICATIONS

The present application is a utility application based upon prior filed U.S. Provisional application Ser. No. 60/556,953, filed Mar. 26, 2004 that is incorporated herein by reference and relied upon for priority.

BACKGROUND OF INVENTION

1. Field of the Invention

The invention relates generally to a foot orthotic, and more particularly to a lightweight ventilated foot supporting orthotic for insertion into a shoe.

2. Background

A foot orthotic is a device for insertion into a shoe and under a user's foot to provide support in selected areas of the foot thereby facilitating alignment of the bones and joints of the foot and the human body supported by the foot.

SUMMARY OF INVENTION

A lightweight ventilated foot supporting orthotic made of strong, resilient, durable plastic that is resistant to stress induced fractures.

Other aspects and advantages of the invention will be apparent from the following description and the appended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a useful orthotic for foot support.

FIG. 2 is a top plan view of the orthotic shown in FIG. 1.

FIG. 3 is a side view of the orthotic shown in FIGS. 1-2.

FIG. 4 is a bottom plan view of the orthotic shown in FIGS. 1-3.

FIG. 5 is a side cross-sectional view along a lateral centerline (front-to-heel) of an orthotic of FIGS. 1-4, taken along section line 5-5 of FIG. 4, according to one embodiment of the present invention.

FIG. 6 is an end cross-section view of the orthotic shown in FIGS. 1-5, taken along section line 6-6 in FIG. 4.

FIG. 7 is a side cross-sectional view along a lateral centerline (front-to-heel) of an orthotic shown in use in a shoe shown in phantom lines according to one embodiment of the present invention.

DETAILED DESCRIPTION

It has been found that the anatomical contour of the human foot is less than ideal when it is considerably planar rather than sufficiently arched. It has been recognized that misaligned joints in the foot typically lead to this less than ideal contour of the foot. Leaving this condition untreated can lead to minor complications such as blisters or calluses or can lead to more serious consequences such as diminished capacity for certain types of movement. It has also been found that in many cases the insole of a shoe is also generally planar and does not provide appropriate support and alignment for the foot.

Over-the-counter sole inserts, arch supporting devices or orthotics are often used to reduce pain and discomfort associated with misaligned joints in the foot. More specialized plantar support members, known as orthotics, are commonly used to biomechanically adjust misaligned joints in the foot and/or to support the foot in proper alignment. Orthotics function to optimally align joints in the foot. This is particularly important during the gait cycle of the foot during human movement by walking or running. The use of orthotics has been successful in realigning the foot for increased comfort. However, it has been found that some patients prefer a thin orthotic that fits conveniently within a normal size shoe without adding significant weight while providing substantial foot adjustment, foot support, or both. It has also been found to be desirable to provide ventilation through the orthotic between the sole of the foot and the shoe.

Therefore, the present invention provides a durable foot orthotic that is thin and lightweight yet provides strong contoured support. The orthotic is made of selected moldable polymeric materials that have properties discovered to be useful for the purposes of providing an orthotic according to the present invention. Such useful characteristics include being moldable into a thin yet highly contoured shape that is sufficiently rigid to provide the required aligning support to the sole of the user's foot. The material is one that is usefully lightweight, relatively hard yet is resiliently flexible so that under high loading, as with jumping or running, it can flex yet it returns to its prior molded contour shape as though it had “a shape memory.” The material is relatively inert in the environment of a shoe including possible heat, moisture, and natural chemical conditions of human skin and perspiration. Further the material has a relatively high modulus of elasticity and modulus of flexure. It is also resistant to stress fracture after repeated flexure below its elastic strain limits and is not susceptible to notch stress risers so that ventilation holes and lightening pockets may be formed without resulting in unacceptable stress cracking or fatigue failure. Thus, the material is one that has a characteristic of being strong, durable, and resistant to deformation and fracture under repeated flexure.

One example of a material found by the inventor to usefully meet the characteristics discovered to be useful for the purposes of the present invention is a plastic or polymeric material known as Acetal. A particular Acetal polymer thermoplastic material available from the DuPont Company marketed under the trademark Delrin® and designated 500P NC010, Medium Viscosity, has been found to be useful for certain aspects of the present invention. Another Acetal polymer thermoplastic material available from the DuPont Company marketed under the trademark Delrin®100 ST also has been found by the inventor to be particularly useful because of its combination of supporting strength and flexible resiliency with out breaking giving it a characteristic that the inventor has termed “a shape memory”. The material is also tough and resists cracking due to stress risers or due to repeated partial loading below the yield point. This particular material comprises more than about 66% Acetal polymer, less than about 30% elastomer, less than about 3% stabilizer, less than about 2% carbon black, and less than about 0.005% formaldehyde bound in a thermoplastic polymer. This material is also relatively inert in the environment of a shoe including possible heat, moisture, and natural chemical conditions of human skin and perspiration. Further the material has a combination of strength, stiffness, hardness, dimensional stability, toughness, fatigue resistance, solvent and fuel resistance, abrasion resistance, low wear and low friction. In particular a relatively high modulus of elasticity and modulus of flexure combined with high toughness and impact resistance, and especially notched impact resistance and is not susceptible to notch stress risers so that ventilation holes and lightening pockets may be formed without resulting in unacceptable stress cracking. It is also resistant to stress fracture after repeated flexure below its elastic strain limits so that fatigue failure is reduced.

Shown in FIGS. 1-4 is an orthotic 10 for insertion into a left shoe, between the sole of a shoe and the sole of a user's foot (not shown). A corresponding orthotic (not shown) for a right shoe may be formed by reversing the symmetry along a lengthwise center line, designated 12 for convenient reference, and extending from a front portion 11 to a heel portion 13 of the orthotic 10. The orthotic 10 includes a top surface 14, a bottom surface 16, and a perimeter edge 18. It will be observed that the front 11 is designed to terminate at a location corresponding to metatarsal area adjacent to or slightly posterior to the ball of the foot. Other orthotics with front portions extending to the toe might also be used although for purposes of lightweight while providing appropriate metatarsal and arch support to the foot the orthotic 10 as depicted has been found to be useful.

The orthotic 10 is molded of a thermoplastic material having the characteristics discovered to be useful according to the present invention. A thin contoured plantar body 9 is formed having a top contoured surface 14 and a bottom contoured surface 16 with a narrow, rounded or otherwise smoothed edge 18 interconnecting the top and bottom surfaces 14 and 16. The top surface 14 is formed with a contoured surface designed to contact and support the human foot while inside a shoe 8 (see FIG. 7). In the example embodiment shown, the top surface 14 includes two concave regions 14 a and 14 b that converge on a convex region 14 c at a position corresponding to the metatarsal area of the foot. Another concave region 14 d is formed generally centrally located at a position corresponding to the heel of the foot toward the heel portion 13 of the body 9 of orthotic 10. A convex region 14 e is formed at the arch portion 20 of the orthotic 10. In other embodiments, the top surface 14 may include other types of contours found desirable for supporting and aligning a particular user's foot. The bottom surface 16 includes a contoured surface with regions such as 16 a and 16 b approximately following the contours of the top surface 14 designed to contact the interior sole of a shoe and to provide partially flexible support in upwardly projecting areas.

The top surface 14 may also diverge from the shape of the bottom surface 16 in certain areas to provide additional alignment support to the joints of the foot. For example, the metatarsal support region 14 c may be curved upward away from the bottom surface 16 c at the metatarsal area so that the body 10 may be thicker at the metatarsal area 14 c to provide upward support, where it is desirable to insure that upward alignment support is maintained relative to adjacent areas of the foot. For example, in the thick region the body may be about 0.45 cm thick. For another example, at the top heel surface 14 d may be closer to surface 16 d to allow the heel of the wearer to be comfortably positioned downward toward the sole of the shoe. For example the body may be about 0.15 cm thick in the central heel region. Thus, region 16 c maybe relatively flat, or less concave, than the top portion 14 c is convex and the orthotic may be thicker or thinner in particular regions. The body is generally thin. This feature is useful for fitting easily within a wearer's shoe, for providing a light weight device, and for providing space between the orthotic and the insole of the shoe to allow the ventilation holes to be effective. For example, an orthotic according to one embodiment of the invention may have a maximum thickness less than about 0.5 cm. In another example the thickness at the central metatarsal may be about 0.5 cm and the thickness in the heel region may be more than about 0.1 cm. Variations in the thickness of the support body 9 in a range of about 0.5 cm to about 0.1 cm is not by itself sufficient to provide the required support and alignment. Particularly, at the arch 20 of the foot, proper alignment may require supporting the arch of the user's foot above the insole of the shoe more than about 1 cm and up to more than about 2 cm. Thus according to embodiments of the invention the contour support at the arch is usefully provided by the upwardly arched contour shape and the strength of the selected plastic material of orthotic body 9 to provide the foot with support and to hold its contour shape. Thus, according to these embodiments the orthotic device does not rely only upon the variations in the thickness and the incompressibility of a more flexible rubber orthotic with varied thickness. When heavy loading occurs the thin orthotic allows flexure in the upwardly arched areas such as at the raised arch 20 and surface regions 14 e and 16 e may flex downward toward the insole of the shoe. The metatarsal area of the foot is supported upward by top surface 14 c both by the contour shape and also by slightly thicker material in the metatarsal region as discussed above. In other embodiments, the top surface 14 may include other variations in the contour shape, however the contour shapes of the top 14 and the bottom 16 surfaces are generally similar to maintain an overall thin lightweight orthotic.

The edge 18 follows the perimeter shape of the contour surfaces 14 and 16 and terminates at the shape of the inside of the shoe as shown in FIGS. 2 and 4, to fit securely against the interior of the shoe and to support the sole of the user's foot. The edge 18 extends from the top surface 14 to the bottom surface 16 on either side of the arch 20 and extends around the heel portion 13 and the front portion 11. In such situations the top surface contour, the length, and side-to-side dimensions are determined for snug fit within the user's shoe size. In the embodiment shown in FIGS. 1-4, the edge 18 is smoothly convex or rounded to avoid sharp corners and to provide for comfortable wearing by a user. In other embodiments, the edge 18 may include other types of contours and might be more or less rounded for other purposes without departing from certain aspects of the invention.

A pattern 30 is formed with a plurality of indentations 32 in the bottom surface 16 to further reduce weight. By using a strong flexible material, such as Acetal, such as the Delrin® polymer material of DuPont or another material having the characteristics as described according to certain aspects of the invention, the volume of material and therefore the weight of the orthotic is reduced. Reducing the volume can also reduce the cost because less material is required.

The use of the strong, flexible and stress fracture resistant material, such as the Delrin® and Acetal materials described above, also allows the orthotic to be formed both thin and with a plurality of ventilation holes 40 extending between the top surface 14 and the bottom surface 16. Normally such ventilation holes might be formed in a softer and more flexible polymer having “rubbery” characteristics, such as an ethyl vinyl acetate (EVA) material without adverse consequences. However such materials will not support the contour shape except by compression strength at regions of the orthotic having increased thickness. Such ventilation holes have not previously been successful in a thin orthotic that depends upon bending strength for supporting the desired foot alignment contour shape.

Aspects of the invention as described will be further understood with reference to the lateral cross-section shown in FIG. 5 and the transverse cross-section shown in FIG. 6. The lateral cross section view of FIG. 5 is taken at an imaginary vertical plane through the lateral center line at section line 5-5 of FIG. 4 and the transverse cross section view of FIG. 6 is taken at an imaginary vertical plane through the orthotic 10 perpendicular to the length of the first orthotic at a section line 6-6 as indicated in FIG. 4. As shown in FIGS. 5 and 6, the orthotic 10 is for insertion into a left shoe. A corresponding orthotic for insertion into a right shoe (not shown) may be formed by reversing the symmetry along the lateral centerline 12. The thin orthotic will facilitate use by those who might not tolerate a thicker orthotic.

FIG. 7 shows a cross-section of an orthotic device 10 inserted into footwear 50 such as a shoe 50 (shown in phantom lines) of a user. The orthtic device 10 is placed against the insole 52 of the shoe 50 and, because of the arch contour shape, touches the insole at least in a forward area 54 adjacent to the metatarsal area of the user's foot and at a rearward area 56 adjacent to the heel of the user's foot. An arch top surface contour region 14 f of the orthotic and also a bottom surface contour 16 f are positioned above the insole at the arch area 58 of the insole. In some embodiments the arch height 60, defined by the spacing between the top surface arch contour 14 f and the insole, is usefully more than about 1 cm and in some embodiments the arch height 60 may be up to about 2 cm or more. Even thought the support body is thinner than the desired height 60 for supporting the arch of the foot, the combined thickness of the support body 9 and the clearance distance 62 supported by the strength of the polymer material of the orthotic 10 provides upward support to the arch of the user's foot.

As described above the thickness of the orthotic is generally maintained within a relatively thin range and less than the desired arch support height. Minor variations in thickness may be provided for positive compression support in particular areas while bending strength of the material is relied upon for supporting the contour shape in other areas where a certain amount of limited flexure bending is permitted. The indentations 32 further reduce weight in a pattern that continues to provide the required flexural bending strength. There are ribs 34 of the pattern that extend between the indentations 32. The ribs 34 may also be thicker than other areas of the orthotic to provide strength to support the arch and also to provide positive compression support against the insole of the shoe in the metatarsal area. The ventilation holes 40 have a maximum dimention 41 that extends through the orthotic. The maximum dimension 41 may for example be the diameter of a circular hole, where circular holes are formed to further reduce stress rising corners, or it may be a diagonal or other maximum dimension of a polygon shaped hole. The indentations 32 are usefully formed having a maximum dimension larger than the maximum dimension of the holes 40 and surrounding the ventilation holes 40. Although it is not required in every instance, the holes 40 are usefully located within the indentations 32 to facilitate ventilation, as with air and moisture flow into, and out of, the cavities formed by the indentations 32. Thus, even when the bottom surface 16 of the orthotic body 9 is compressed against an insole 52 of a shoe 50 there can be ventilation through the holes 40 where they are positioned in and fluidically communicate with indentations 32.

A thin, lightweight orthotic 10 may be molded with substantially the same support or corrective shape of other more traditional orthotic arch supports and maintaining the same or a similar contour shape of the top surface 14 and the bottom surface 16 using a thermoplastic Acetal polymer material determined by the inventor to be useful for that purpose. Such a thin foot orthotic device, made with the selected Acetal polymer material, can also have a useful life that is comparable to other thicker foot orthotics. The thin orthotic will facilitate use by users who might not tolerate a thicker orthotic. Moreover the orthotic can be made with sufficient arch support and clearance between the orthotic and the insole, with ventilation holes, and/or with ventilation hole extending into cavities defined by indentations to facilitate ventilation, while continuing to resist cracking whether due to stress or fatigue.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments and other combinations of the various inventive features can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should not be limited to a particular embodiment or example set forth but should include other equivalents that embody the discovered concepts, structures, constructions, or structures set forth herein. 

1. A foot orthotic comprising: a thin contoured foot support body having a size and shape for fitting into a user's footwear, the support body having a top contoured surface and a bottom contoured surface with an edge interconnecting the top and bottom contoured surfaces, the contoured surfaces defining an upward arch between a metatarsal area and a heel area to provide upward support to an arch of a user's foot when the orthotic is inserted into the user's footwear, wherein the arch area is at least partially spaced above the insole of the footwear; and a plurality of spaced apart ventilation holes formed in the support body between the top and bottom contour surfaces to allow the interchange of air and moisture therethrough.
 2. The foot orthotic of claim 1, wherein: the bottom contour shape generally corresponds in shape to the top surface spaced a short distance, defined by the thickness of the support body, from the bottom surface so that the support body of the orthotic has thickness variations between about 0.5 cm, at a thickest part, to about 0.1 cm, at a thinnest part, to form a thin lightweight support body such that the thickness variations provide additional alignment support to the user's foot.
 3. The foot orthotic of claim 1, wherein: the support body comprises a molded Acetal polymer material.
 4. The foot orthotic of claim 1, wherein: the support body comprises a molded polymer material composition comprising more than about 66% Acetal polymer and less than about 30% elastomer.
 5. The foot orthotic of claim 4, wherein: the support body comprises a molded polymer material comprising more than about 66% Acetal polymer, less than about 30% elastomer, less than about 3% stabilizer, less than about 2% carbon black, and less than about 0.005% formaldehyde bound in a thermoplastic polymer.
 6. The foot orthotic of claim 1, wherein: the support body has varied thickness such that along a front-to-heel cross-section the metatarsal area of the support body is thicker than the arch support area, and the arch support area is thicker than the heel area.
 7. The foot orthotic of claim 6, wherein: the arch area of the support body comprises an upward contour greater than about 1 cm so that the arch of the user's foot is supported by the orthotic above the insole of a user's footwear to provide both arch support to the user's foot and ventilation thereunder.
 8. The foot orthotic of claim 1, wherein: the support body has varied thickness such that the support body is thicker in the middle and thinner at either side along a side-to-side cross-section through the metatarsal area.
 9. The foot orthotic of claim 1, wherein the ventilation holes in the support body comprise a plurality of spaced apart holes having a first maximum dimension extending entirely through the support body, and further comprising: a plurality of indentations in the bottom surface each surrounding one of the holes and having a maximum dimension greater than the maximum dimension of the hole it surrounds and extending partially into the support body and surrounding the hole to facilitate ventilation thereunder.
 10. A foot orthotic comprising: a thin contoured foot support body having a size and shape for fitting into a user's footwear, the support body having a top contoured surface and a bottom contoured surface with an edge interconnecting the top and bottom contoured surfaces, the contoured surfaces defining an upward arch between a metatarsal area and a heel area to provide upward support to an arch of a user's foot when the orthotic is inserted into the user's footwear, wherein the arch area is at least partially spaced above the insole of the footwear; and wherein, the support body comprises a molded Acetal polymer material, having sufficient strength and resiliency to flexibly support the arch of a user's foot above the insole of the user's footwear.
 11. The foot orthotic of claim 10, wherein: the support body comprises a molded polymer material comprising more than about 66% Acetal polymer, less than about 30% elastomer, less than about 3% stabilizer, less than about 2% carbon black, and less than about 0.005% formaldehyde bound in a thermoplastic polymer.
 12. The foot orthotic of claim 10, wherein: the arch area of the support body comprises an upward contour greater than about 1 cm so that the arch of the user's foot is supported by the orthotic above the insole of a user's footwear and so that an open space is provided thereunder.
 13. The foot orthotic of claim 10, wherein: the support body has varied thickness such that along a front-to-heel cross-section the metatarsal area of the support body is thicker than the arch support area, and the arch support area is thicker than the heel area.
 14. The foot orthotic of claim 13, wherein: the bottom contour shape generally corresponds in shape to the top surface spaced various short distances from the top surface so that the support body of the orthotic has thickness variations between about 0.5 cm, at a thickest part, to about 0.1 cm, at a thinnest part, to form a thin light weight support body such that the thickness variations provide additional alignment support to the user's foot.
 15. The foot orthotic of claim 10, further comprising: a plurality of spaced apart ventilation holes formed in the support body between the top and bottom contour surfaces communicating between the top surface and the space under the arch between the support body and the insole to facilitate ventilation of air and moisture therethrough.
 16. A foot orthotic composed of a strong theromoplastic polymer material, the foot orthotic comprising: a top contoured surface having a shape defining an upward arch between a metatarsal area and a heel area; a bottom contoured surface having a shape generally corresponding to the shape of the top contour surface and spaced varying short distances from the top surface; an edge interconnecting the top and bottom contoured surfaces; and wherein the top contour surface the bottom contour surface and the edge define a support body sized and shaped to fit into footwear and partially against the insole of the footwear and to provide upward support to an arch of a user's foot such that the bottom contour surface is spaced apart from the insole at the arch to allow ventilation thereunder when the orthotic is inserted into the footwear.
 17. The foot orthotic of claim 16, wherein: the arch area of the support body comprises an upward contour greater than about 1 cm so that the arch of the user's foot is supported by the orthotic above the insole of a user's footwear to provide for ventilation therunder.
 18. The foot orthotic of claim 16, wherein: wherein, the support body comprises a molded Acetal polymer material, having sufficient strength, toughness, resistance to fatigue, and resiliency to flexibly support the arch of a user's foot above the insole of the user's footwear without premature failure.
 19. The foot orthotic of claim 16, wherein: the support body comprises a molded polymer material comprising more than about 66% Acetal polymer, less than about 30% elastomer, less than about 3% stabilizer, less than about 2% carbon black, and less than about 0.005% formaldehyde bound in a thermoplastic polymer.
 20. The foot orthotic of claim 16, wherein: a plurality of spaced apart ventilation holes formed communicating between the top and bottom contour surfaces to allow air and moisture flow therethrough. 